The present invention relates to a safety blister package for enclosing medication or pills.
As disclosed in U.S. Pat. No. 3,809,211, one of the problems facing today""s parents is keeping medication or pills beyond the reach of their children. Children do not have the ability to recognize the risk involved in consuming non-prescription medication. Because of this fact there is an urgent need for a package from which pills are readily accessible to the adult, but not accessible to the child.
Press-through packs or xe2x80x9cblisterxe2x80x9d packs are commonly used today to package units of medication or pills for oral ingestion. The press-through package is made up of a blister sheet, typically a clear, preformed polyvinyl chloride or polystyrene with flexible bubbles which form separate compartments or blisters for one or more pills; and a second rupturable backing sheet, like an aluminum foil or paper sheet, which has been attached to the blister sheet. The metal foil is attached by heat-sealing, solvent welding, gluing, or otherwise adhering the foil sheet to the blister sheet. A tablet is removed from a blister by pressing on the flexible blister which in turn forces the tablet against the foil, rupturing the foil, and ejecting the tablet.
It is sometimes desirable in making such a press-through package to include between the blister and backing sheets a rigid tray in which there are holes which coincide with the blisters in said blister sheet. The rigid tray is used to protect the pills from contamination and mechanical damage and may contain printed instructions as to the type of pill or the time a particular dosage is to be taken and with an indication of the dosage that has already been taken.
The recent trend in the packaging of medication has been to provide packages which will be safe, even if found by children. Most developments in the xe2x80x9cchild-resistantxe2x80x9d line have been directed to the improvement in pill bottles. In this regard, safety caps have been devised which require a certain series of pushes and turns in order to open the bottle. However, there has been little development in the area of xe2x80x9cchild-resistantxe2x80x9d press-type blister packages with which this invention is concerned.
Packages which have used more than one backing sheet on a press-through blister-type package have not used a layer of backing material which cannot be ruptured. The prior layers which have been used to cover the rupturable layer, have been made from paper or foil and may have been scored or weakened so that all backing layers can be ruptured to press a pill through the package. These additional prior art backing layers have been used for the purposes of providing printed information on the back of the pill package and for additional sealing engagement to protect the pills from the environment. For example, see the following U.S. Pat. Nos.: Nagy, U.S. Pat. No. 3,503,493; Osborn, U.S. Pat. No. 3,621,992; Sorensen, U.S. Pat. No. 2,317,860; and Heller, U.S. Pat. No. 3,387,699. In each of these patents the multiple backing layers used on the blister or press-through type pill package can be easily ruptured or peeled away and are not strong enough to provide xe2x80x9cchild-resistance.xe2x80x9d
One attempt at providing a xe2x80x9cresistantxe2x80x9d blister-type pill package, can be seen in the Helstrom U.S. Pat. No. 3,472,368. In this patent, there is no second backing member which is peeled away to expose the rupturable layer as will be disclosed in describing the present invention. This package is supposedly xe2x80x9cchild-resistantxe2x80x9d simply by providing a rupturable sheet which is ruptured with difficulty. The Helstrom patent, therefore, relies on the child""s weakness as the necessary element to prevent him from opening the package.
Compere, U.S. Pat. No. 3,921,805, discloses a pill package which requires knowledge of the package opening procedure rather than a minimum amount of strength for opening said package. A person likely to be taking pills is not generally very strong. Quite often, the strength of a child is greater than the strength of an adult who is ill. Because of this fact, this invention was developed to provide a pill package which can be opened by an instructed adult who may have no more strength than the average child. The child who is uninstructed on the opening of the disclosed package will not be able to reach the package contents. The present invention, therefore, relies on the superior knowledge of the adult rather than his superior strength.
A primary object of the present invention is to provide a xe2x80x9cchild-resistantxe2x80x9d pill package which can be easily opened by one who has been given instructions on how to do so, but cannot be opened by the uninstructed child.
Another object of the present invention is to provide a pill package which, when opened, makes only one dosage of pills accessible to the user, which dosage, of course, is less than a harmful dosage.
Another object of the present invention is to provide a pill package in which any desired number of pills can be made accessible upon opening.
Another object of the present invention is to provide a pill package in which one pill or one dosage of pills can be removed from the package while the remaining pills can be maintained in an air-tight enclosure.
Another object of the present invention is to provide a pill package in which the use of-cumbersome bottles is not required.
Another object of the present invention is to provide a pill package in which each individual pill can be separately packaged so that the desired dosage can be carried by the user without the necessity of carrying excess pills.
Another object of the present invention is to provide a pill package which requires an additional opening step to remove each additional pill.
Another object of the present invention is to provide a safety pill package which children, on average, cannot open without the aid of tools.
Yet another object of the present invention is to provide a pill package in which opening of the package makes accessible fewer than a dangerous number of units of medication. The number of units exposed upon each opening of the package can be varied depending upon the toxicity of the packaged medication.
The present invention provides a blister package which is similar to the common blister package, but which has a strong flexible backing sheet which encloses each blister. The strong flexible backing sheet is secured to the back of the blister sheet in such a manner that when secured, the backing sheet is not pushed away from the blister sheet when pressure is put on the blister-side of the package in an attempt to push the pill through the package. For a user to be able to remove a pill from the package, the strong backing sheet must first be peeled away. So long as the required adherence is obtained, the strong backing sheet can be secured to the blister sheet by heat sealing, solvent welding, gluing or otherwise adhering the two sheets together. A preferred method is by heat-sealing.
There are hundreds of heat-sealed coating formulations which can be used to provide heat-sealability between the layers of the package laminate of the present invention. These heat-seal formulations are commonly used in making foil/paper and resin sheet/resin sheet laminates for soap wraps, carton overwraps, cereal liners, cookie wraps, and other uses. The heat-seal formulations are typically a water dispersion of a vinyl resin or a vinyl resin containing wax for providing lower heat-sealing temperatures. The vinyl resin can be ion-linked and acid-modified ethylene interpolymers known as ionomer resins. Wax and other modifiers further extend the range of performance properties.
The preferred heat-seal formulations are water dispersions of ethylene interpolymers, for example ethylene/vinyl acetate interpolymers. The vinyl resin formulations combine broad adhesion properties with moderate hot tack. Modifiers such as pigments, waxes or other resins can be used.
It is preferred to apply the heat-seal coatings in an amount of about 7 grams/meter2. The coatings can be applied by common methods, for example, curtain coating or roller coatings as known in the art.
The blister sheet is made in a known manner and is made from common blister sheet material such as polyvinyl chloride, and copolymers and terpolymers of vinyl chloride, for example the terpolymer of polyvinyl chloride/polyethylene/polypropylene.
The backing sheet should have a layer or sheet of a strong flexible polymeric material of sufficient strength that a pill cannot be hand-forced through the polymeric material. A sheet of polyester material has been found to have sufficient strength to prevent a pill from being forced therethrough. A preferred polyester material is polyethylene terephthalate.
A foil sheet can also be used as part of the backing sheet if a barrier resistance coating is needed to prevent moisture from penetrating into the blister. A metal foil, such as aluminum, having a thickness as small as 0.0008 inch is sufficient.
A sheet of paper for the purpose of printing may also form part of the backing sheet. Bleached kraft paper having a basis weight of roughly 30 pounds is preferred. Dates, numbers, or a description of the package contents can be printed on the paper for consumer information.
The various layers comprising the backing sheet can be laminated to form a single laminated sheet prior to applying the backing sheet to the blister sheet, or the backing layers can be secured together at the same time they are adhered to the blister sheet. The preferred method of laminating is by using heat-seal coatings, as previously described. It is usually desirable to provide a paper sheet as the sheet farthest from the blister sheet so that printing is easily read from the bottom or non-blister side of the package. However, if it is not necessary to prevent moisture penetration into the blister, the printed paper can be positioned next to the transparent blister sheet and read through the blister sheet from the top of the package.
The strong polymeric sheet, foil sheet, and paper can be applied to the blister sheet in any order except that the paper sheet cannot be positioned next to the blister sheet if it is necessary to prevent moisture from entering the blister. Thus, the strong polymeric sheet can be positioned next to the blister sheet or intermediate between the foil and paper sheet, or as the sheet farthest from the blister. If the paper sheet is between the foil and strong polymeric sheet, the polymeric sheet is preferably transparent so that printing on the paper can be read by the consumer.
When applied as a single lamination structure, the layers of the backing sheet can be secured together by heat-sealing, solvent welding, gluing, applying sheets of adhesive materials between the layers, or otherwise adhering the layers together. For example, a sheet of extruded polyethylene can be included between the sheet of strong flexible material and the foil sheet and likewise between the foil and paper sheet. The extruded polyethylene will adhere the three sheets together upon the application of pressure without the necessity of heat-sealing. It is preferred to use an extruded polyethylene sheet or film. Heat-seal coatings can be used in addition to intermediate adhesive layers.
After securing the blister sheet to the backing sheet, the backing sheet cannot be forced to disengage the blister sheet by applying pressure on the pill from the blister-side of the packet. However, the backing sheet can readily be peeled from the back of the package so that the blister contents can be removed. The seal between the blister sheet and backing sheet must be strong enough so that when pressure is applied to the blister, the flexible backing sheet remains in contact with the blister sheet. The backing must be strong enough so that with the backing sheet engaged, a pill cannot be forced through the backing sheet by applying pressure to the pill from the blister-side of said package.
A strong polyester which has been found particularly effective as at least one component of the backing sheet is polyethylene terephthalate. The thickness of the polyester is preferably about 48 gauge. This gauge also helps prevent biting of the package. However, any plastic with strength sufficient to prevent a pill from being hand-forced therethrough can be used for this purpose.
At least one xe2x80x9cnon-throughxe2x80x9d score line is made in the exposed surface of the blister sheet. The score line extends from one edge of an individual blister unit to an opposite or adjacent edge, that is across the corner of the blister unit. The score line penetrates the blister sheet only partially. It does not extend completely through the thickness of the blister sheet. When the blister unit is angulated or flexed at the score line, the blister sheet fractures. The smaller portion of the fractured blister sheet, still bonded to the backing sheet, acts as a tab for peeling the backing sheet from the blister sheet, exposing the blister contents.
The depth of the score line into the blister sheet is critical for producing an effective package. A non-through score line of minimal depth will produce a more effective child resistant package than one with a deeper cut and a non-through score line of maximum depth will produce a more effective senior adult use package than one having a lesser depth. An effective score depth is required to produce a package that is both child resistant and senior effective for a given product toxicity level.
The depth of a score line in a blister package has previously been of no great consequence. However, it has recently been shown that the depth of a score line will significantly enhance the ability of the blister package to pass child resistance (C.R.) tests, as well as senior effectiveness (S.E.) tests. Child resistance tests gauge the ability of a child to successfully open a package within a prescribed time, prior and after having been shown by an adult the proper manner to open the package. Senior effectiveness tests help determine whether typical seniors can successfully open the package.
It has been shown through C.R. testing that as the depth of the score line increases, the blister package becomes senior effective and as it decreases, the blister package becomes more child resistant. A score line depth can be established that creates the optimal C.R./S.E. blister package. Cut depth settings differing by as little as 0.001 inches have shown clear effects in the C.R. test data. Thus, new relevance has been placed on the depth of the score line in the blister package.
The standards for C.R. and S.E. tests vary, but generally they are evaluated according to the following criteria. For a test package to pass a C.R. test, a group of 200 children aged 3xc2xd to 4 are shown how to open the package. Then, these children are asked to open the package individually. If 80% of the children cannot open the package, it is considered to pass the test. On the other hand, if 90% of the seniors (age 65-70) are able to open the device (in other words, the physical qualities of the device are such that 90% of the seniors are able to open the package even though most children cannot), then it is considered to pass the S.E. test.
In another embodiment of the present invention, a surface pattern or camouflage pattern is created on the blister sheet which further obscures the score line needed to open the package. In a preferred embodiment of the invention the camouflage pattern contains elements arranged in the same direction as the score line. In this manner, the score line and the camouflage pattern visually form a consistent appearance in the blister package, further enhancing the child resistant nature of the blister package.